This invention relates to a motor-driven piston-type valve, and more particularly to such a valve having a slip clutch actuated limit switch to shut off the valve motor when the valve piston encounters a predetermined resistance.
The invention is intended particularly for a piston-type valve. Such valve is often used in fluid-flow systems containing various quantities and sizes of debris and solid particles. It is imperative that the valve contains some type of automatic shut-off system which is needed when the valve piston encounters a predetermined resistance on the opening or closing of the valve.
Therefore, it is an object of the invention to provide a motor-driven piston-type valve having an automatic shut-off mechanism to stop valve actuation when the valve piston encounters a predetermined resistance.
A further object is to provide a valve of the above type having a slip-clutch actuated limit switch to shut off the valve motor when the valve piston encounters a predetermined resistance.
A further object of the invention is to provide a valve of the above type that is simple in construction, inexpensive to manufacture, and highly effective in operation.
Briefly the foregoing objects are accomplished by the provision of a motor-driven piston-type valve including a valve body having a horizontally disposed fluid flow passageway. A valve piston is operatively mounted in the valve body for vertical movement therein to selectively close and open the passageway. An electric motor is operatively connected to the piston to vertically move the same. A slip clutch is operatively interposed between the motor and the piston whereby clutch slippage is effected when the piston encounters a predetermined resistance in its vertical movement. A limit switch is operatively connected to the clutch for triggering by clutch slippage, such limit switch also being electrically connected to the motor, whereby when the piston encounters a predetermined resistance in its vertical movement, resultant clutch slippage triggers the limit switch to stop the motor. The slip clutch includes first and second couplings, with bias means urging the couplings together in mated relation. Each coupling has a plurality of coacting circumferentially disposed recesses formed in their opposed mating surfaces, with the recesses in one coupling disposed opposite the recesses in the other coupling. Ball bearings are disposed in the recesses. The recesses in the first coupling are cylindrical-shaped, and the recesses in the second coupling are cone-shaped. The piston is cylindrical-shaped, such piston having a threaded stem connected to the clutch, with the threaded stem also extending through a mated threaded aperture in the valve body whereby motor actuation drives the piston to operate the valve. A gear box is interposed between the motor and the slip clutch to drive the piston at a predetermined speed.